Loading ...Debugging Tip: Trace the Process and See What It is Doing with strace
strace is a useful diagnostic, instructional, and debugging tool. It can save lots of headache. System administrators, diagnosticians and trouble-shooters will find it invaluable for solving problems with programs for which the source is not readily available since they do not need to be recompiled in order to trace them. This is also useful to submit bug reports to open source developers.
Each line in the trace contains the system call name, followed by its arguments in parentheses and its return value.
Run strace against /bin/foo and capture its output to a text file in output.txt:
$ strace -o output.txt /bin/foo
You can strace the webserver process and see what it's doing. For example, strace php5 fastcgi process, enter:
$ strace -p 22254 -s 80 -o /tmp/debug.lighttpd.txt
To see only a trace of the open, read system calls, enter :
$ strace -e trace=open,read -p 22254 -s 80 -o debug.webserver.txt
Where,
- -o filename : Write the trace output to the file filename rather than to screen (stderr).
- -p PID : Attach to the process with the process ID pid and begin tracing. The trace may be terminated at any time by a keyboard interrupt signal (hit CTRL-C). strace will respond by detaching itself from the traced process(es) leaving it (them) to continue running. Multiple -p options can be used to attach to up to 32 processes in addition to command (which is optional if at least one -p option is given).
- -s SIZE : Specify the maximum string size to print (the default is 32).
Refer to strace man page for more information:
$ man strace
Continue reading rest of the How to report / Find a bug under Linux series.
Contents
- Debugging Tip: Trace the Process and See What It is Doing with strace
- valgrind - Linux Tools For Debugging And Profiling Programs ( bug reporting tool )
- ktrace - FreeBSD / Mac OS X Process Tracing and Reporting Tool
Want to stay up to date with the latest Linux tips, news and announcements? Subscribe to our free e-mail newsletter or RSS feed to get all updates.
You can Email this page to a friend.
You may also be interested in other helpful articles:
- strace and the GDB Debugger mini howto
- ktrace - FreeBSD / Mac OS X Process Tracing and Reporting Tool
- Temporary memory files and shell scripts
- Lighttpd php segfault at 0000000000000040 rip 0000003e30228278 rsp 0000007fbffff708 error 4
- valgrind - Linux Tools For Debugging And Profiling Programs ( bug reporting tool )
Leave a Reply
We encourage your comments, and suggestions. But please stay on topic, be polite, and avoid spam. Thank you very much for stopping by our site!
Tags: bug reports, core dump, debug, linux strace, process id, ptrace, red hat linux, strace, strace command, strace example, strace rpm, system call, system calls, trace output
Recent Comments
Today ~ 12 Comments
Today ~ 6 Comments
Today ~ 21 Comments
Today ~ 1 Comment
Today ~ 1 Comment